Spin Processing Method And Apparatus

ABSTRACT

There are provided a spin processing method and a spin processing apparatus with which the improvement of a processing speed in spin processing can be compatible with the saving of a processing solution. The spin processing method comprises holding and fixing the wafer on the upper surface of the spin table, and supplying the processing solution to the surface of the wafer by the predetermined amount while rotating the spin table, to process the surface of the wafer, wherein the processing solution is supplied while the wafer is heated and maintained at the predetermined temperature, to process the wafer. The predetermined temperature for heating the wafer is equal to or higher than 25° C.

TECHNICAL FIELD

The present invention relates to a spin processing method and a spinprocessing apparatus with which a processing speed of spin processingsuch as spin etching processing or spin washing processing can beimproved and a processing solution can be saved.

BACKGROUND ART

In conventional spin processing, a method of increasing a temperature ofa processing solution and holding a wafer temperature at a spinprocessing point is used.

An apparatus shown in FIG. 5 has been known as an apparatus forperforming the conventional spin processing, for example, spin etchingprocessing. In FIG. 5, reference numeral 10 denotes a conventional spinetching apparatus which includes a spin table 14 provided to berotatable by a rotational shaft 12. A wafer holding means 16 for holdinga wafer W is provided on an upper surface of the spin table 14.Reference numeral 18 denotes a chemical solution supply nozzle providedabove the wafer holding means 16. The chemical solution supply nozzle 18is connected with a chemical solution circulating and heating tank 22through a connection pipe L1 to which a chemical solution pump P1 isprovided. The chemical solution circulating and heating tank 22 has afunction for storing an etching solution 20 and performing circulationand heating thereon.

Reference numeral 24 denotes a chemical solution supply bottle forstoring the etching solution 20, which is connected with the chemicalsolution circulating and heating tank 22 through a connection pipe L2 towhich a pump P2 is provided and which acts to replenish the etchingsolution when the etching solution stored in the chemical solutioncirculating and heating tank 22 reduces. Reference numeral 26 denotes aheater means provided adjacent to the chemical solution circulating andheating tank 22, which is provided in a chemical solution circulatingpipe L3 to which a circulating pump P3 is provided and which has afunction for heating the etching solution circulating in the chemicalsolution circulating pipe L3. Reference numeral 28 denotes a temperaturesensor which is provided so as to be able to be immersed in the chemicalsolution circulating and heating tank 22 and which detects a temperatureof the etching solution 20 in the chemical solution circulating andheating tank 22.

The temperature sensor 28 is electrically connected with a temperaturecontrol circuit 30 through an electrical wire E1. The temperaturecontrol circuit 30 is electrically connected with the heater means 26through an electrical wire E2. The heater means 26 is controlled basedon a signal from the temperature control circuit 30, so the temperatureof the etching solution 20 can be adjusted to a predeterminedtemperature.

According to the above-mentioned structure, the etching solution 20which circulates in the chemical solution circulating and heating tank22 and is maintained at the predetermined temperature is supplied fromthe chemical solution supply nozzle 18 to an upper surface of the waferW by a predetermined amount, thereby performing predetermined spinetching processing. In the spin etching processing, the temperature ofthe etching solution 20 in the chemical solution circulating and heatingtank 22 is continuously detected by the temperature sensor 28 and adetection temperature signal therefrom is sent to the temperaturecontrol circuit 30. The heater means 26 is controlled based on thesignal from the temperature control circuit 30, so the etching solution20 is maintained at the predetermined temperature.

However, in the above-mentioned spin etching apparatus, it is necessaryto heat an etching solution required to process a predetermined numberof wafers in a standby state, so deterioration with time of the etchingsolution during the standby state becomes a problem. The standby of theetching solution at a high temperature becomes a problem in view of notonly deterioration with time but also safety.

There is another problem that the holding of the temperature at a spinetching processing point (upper surface of the spin table 14) requiresan increase in the amount of etching solution to be supplied and theimprovement of a processing speed directly leads to an increase in theamount of etching solution to be used. The above-mentioned conventionalapparatus has a problem that an etching solution supplying circuit iscomplicated, thereby causing an increase in cost.

In order to increase the etching processing speed in the spin etchingprocessing, it is necessary to adjust the temperature of the etchingsolution to a high temperature. In addition, in order to suppress areduction in temperature at the etching processing point, it isnecessary to increase a chemical solution flow rate. However, when thetemperature of the etching solution is set to a high value in order toincrease the etching processing speed, the etching solution which is notused and in the standby state deteriorates with time. In addition, inorder to prevent the reduction in temperature at the etching processingpoint, the flow rate is increased, so it is necessary to supply theetching solution having an amount of equal to or larger than thatrequired for processing. Therefore, there is a situation that theimprovement of the etching processing speed cannot be compatible withthe saving of the etching solution. Another spin processing such as spinwashing processing has the same problems.

In addition to the above-mentioned method of controlling the temperatureof processing solution such as the etching solution, a method ofcontrolling an atmosphere temperature inside a container of a substrateprocessing apparatus has been known (Patent Document 1).

Patent Document 1: JP 2000-315671 A

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The present invention has been made to solve the above-mentionedproblems of the conventional technique and an object of the presentinvention is to provide a spin processing method and a spin processingapparatus with which the improvement of a processing speed in spinprocessing can be compatible with the saving of a processing solution.

Means for Solving the Problems

To solve above-mentioned problems, a spin processing method according tothe present invention is a spin processing method comprising holding andfixing a wafer on an upper surface of a spin table, and supplying aprocessing solution to a surface of the wafer by a predetermined amountwhile rotating the spin table, to process the surface of the wafer,wherein the processing solution is supplied while the wafer is heatedand maintained at a predetermined temperature, to process the wafer.

The predetermined temperature for heating the wafer is preferably equalto or higher than 25° C., more preferably equal to or higher than 30°C., and most preferably equal to or higher than 35° C. An upper limitvalue of the temperature of the heated wafer may be high as long as theprocessing solution is not boiled. However, an upper limit temperatureof a normal etching solution or washing solution is approximately 99° C.An appropriate amount of supply of processing solution is 1 L/min to0.005 L/min. When the amount of supply exceeds 1 L/min, the temperatureof the supplied processing solution influences the temperature controlof the wafer, which is not preferable. When the amount of supply issmaller than 0.005 L/min, there may be the case where a processingeffect is insufficient.

A spin processing apparatus according to the present inventioncomprises: a spin table rotatably provided and including wafer holdingmeans on an upper surface thereof; a chemical solution supply nozzle forsupplying a processing solution to the upper surface of the spin table;wafer heating means for heating a wafer held and fixed on the uppersurface of the spin table; wafer temperature detecting means fordetecting a temperature of the wafer; and a temperature control circuitfor controlling the wafer heating means based on a detection temperaturesignal from the wafer temperature detecting means.

An N₂ hot jet means for spraying a pressurized and heated nitrogen gas,an air hot jet means for spraying pressurized and heated air, or aninfrared spot light means for emitting infrared light in a spot-shapedmanner can be used as the wafer heating means. In addition, it ispossible to use a heating member (heater) with which a temperature canbe adjusted, which is provided in the wafer holding means.

It is not the gist of the present invention is not to feed an etchingsolution adjusted to a high temperature in a standby state to a spinprocessing point (upper surface of the spin table) as in a conventionalcase, but to increase a temperature of a processed surface of the waferat the spin a processing point to a temperature close to an upper limittemperature of each of the wafer and the processing solution to be used,thereby processing the wafer.

The processing solution (chemical solution) to be supplied in thepresent invention is supplied at a flow rate reduced to a minimum flowrate at which the processed surface of the wafer can be uniformlyprocessed, thereby preventing a reduction in temperature of a surfaceprocessed by the processing solution (chemical solution). Such means isemployed, so it is possible to increase a processing speed and save theamount of processing solution (chemical solution) to be used.

EFFECTS OF THE INVENTION

According to the present invention, the temperature control is performedat the spin processing point, so there is no deterioration with time ofthe processing solution. Therefore, the temperature can be increased toa limit, with the result that the processing can be performed in afastest chemical reaction condition. Thus, according to the presentinvention, an effect capable of improving a production capacity isobtained.

According to the present invention, even when a chemical solution flowrate is minimized, the temperature control is performed at the spinprocessing point, so there is no reduction in temperature. Therefore,when the chemical solution flow rate is smaller, the temperature controlis more easily performed at the spin processing point, which isadvantageous.

According to the present invention, the use efficiency of the chemicalsolution is improved, thereby reducing the amount of the chemicalsolution to be used. In addition, a chemical solution supply circuit issimplified, so a reduction in cost can be expected.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic explanatory side diagram showing a structuralexample of a spin etching apparatus according to the present invention.

FIG. 2 is a schematic explanatory partial cross sectional diagramshowing another structural example of the spin etching apparatusaccording to the present invention.

FIG. 3 is a graph showing a correlation between a hydrofluoric acid flowrate and an etching rate in Experimental Example 1.

FIG. 4 is a graph showing a correlation between a wafer surfacetemperature and an etching rate in Experimental Example 2.

FIG. 5 is a schematic explanatory side diagram showing a structuralexample of a conventional spin etching apparatus.

DESCRIPTION OF SYMBOLS

10: a conventional spin etching apparatus, 11, 11 a: spin processingapparatus of the present invention, 12: a rotational shaft, 14: a spintable, 16: a wafer holding means, 18: a chemical solution supply nozzle,20: an etching solution, 22: a chemical solution circulating and heatingtank, 24: a chemical solution supply bottle, 26: a heater means, 28: atemperature sensor, 30: a temperature control circuit, 32: a waferheating means, 34: a wafer temperature detecting means, 35: an externalpower source, 36: a power supply brush, 38: an electrical wire, E1, E2,E3, E4: electrical wires, L1, L2, L4: connection pipes, L3: a chemicalsolution circulating pipe, P1, P2, P4: chemical solution pumps, P3: acirculating pump, W: a wafer

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be describedwith reference to FIG. 1. The embodiment will be described as an exampleand various modifications can be made without departing from thetechnical idea of the present invention. In FIG. 1, components identicalor similar to the components shown in FIG. 5 will be described withreference to the same reference symbols.

In FIG. 1, reference numeral 11 denotes a spin processing apparatusaccording to the present invention, for example, a spin etchingapparatus, which includes a spin table 14 provided to be rotatable via arotational shaft 12. A wafer holding means 16 for holding a wafer W isprovided on an upper surface of the spin table 14. Reference numeral 18denotes a chemical solution supply nozzle provided above the waferholding means 16. The chemical solution supply nozzle 18 is connectedwith a chemical solution supply bottle 24 for storing an etchingsolution 20 through a connection pipe L4 to which a chemical solutionpump P4 is provided. It is unnecessary to control a temperature of theetching solution 20 stored in the chemical solution supply bottle 24.However, the temperature may be adjusted to a predetermined temperature.FIG. 1 shows an example in which the temperature of the etching solutionis not controlled.

Reference numeral 32 denotes a wafer heating means provided lateral toand above the spin table 14. Examples of the wafer heating means 32include an air hot jet means or an N₂ hot jet means for pressuring andheating air or a nitrogen gas (N₂) and an infrared spot light means foremitting infrared light in a spot-shaped manner. As to be describedlater, a structure in which a heating member (heater) with which atemperature can be adjusted is provided in the wafer holding means 16can be employed for the wafer heating processing means.

Reference numeral 34 denotes a wafer temperature detecting means, forexample, an infrared radiation thermometer, which is provided lateral toand above the spin table 14 and opposed to the wafer heating means 32.The wafer temperature detecting means 34 is electrically connected witha temperature control circuit 30 through an electrical wire E3. Thetemperature control circuit 30 is electrically connected with the waferheating means 32 through an electrical wire E4. The wafer heating means32 is controlled based on a signal from the temperature control circuit30, so the temperature of the wafer W can be adjusted to a predeterminedtemperature.

According to the above-mentioned structure, while the wafer W held onthe spin table 14 by the wafer holding means 16 is heated to apredetermined temperature by the wafer heating means 32, the etchingsolution stored in the chemical solution supply bottle 24 is supplied toan upper surface of the wafer W, whereby predetermined spin etchingprocessing is performed. In the spin etching processing, the temperatureof the wafer W is continuously detected by the wafer temperaturedetecting means 34 and a detection temperature signal thereby is sent tothe temperature control circuit 30. The wafer heating means 32 iscontrolled based on the signal from the temperature control circuit 30,so the wafer W is maintained at the predetermined temperature.

The example is described in which the wafer heating means 32 such as theair hot jet means, the N₂ hot jet means, or the infrared spot lightmeans is separately provided as the wafer heating means 32 shown inFIG. 1. Another structure can be also employed in which the waferholding means 16 is directly heated to heat the wafer W, which will bedescribed below.

Another example of the processing apparatus according to the presentinvention will be described with reference to FIG. 2. In FIG. 2,components identical or similar to the components shown in FIG. 1 willbe described with reference to the same reference symbols.

In FIG. 2, reference symbol Ha denotes a spin processing apparatusaccording to the present invention, for example, a spin etchingapparatus, which includes the spin table 14 provided to be rotatable viathe rotational shaft 12. The wafer holding means 16 for holding thewafer W is provided on the upper surface of the spin table 14.

Reference numeral 33 denotes a heating member (electrical heater)provided to the wafer holding means 16 for heating the wafer W. Acurrent is supplied from an external power source 35 to the heatingmember 33 through power supply brushes 36, 36 and electrical wires 38,38, so the wafer holding means 16 and the wafer W held and fixed by thewafer holding means 16 can be heated. Other structures are identical tothose shown in FIG. 1 and thus the duplicated description is omittedhere. According to the above-mentioned structure, the same operation andeffect as those in the case where the wafer heating means 32 isseparately provided as shown in FIG. 1 can be realized.

As described later in examples, the spin processing method and the spinprocessing apparatus according to the present invention is used toremove an oxide film from the surface of an Si wafer and can be appliedto remove a resist film, an nitride film, or a metal film therefrom.

EXAMPLE

Hereinafter, the present invention will be more specifically describedby way of example. The example will be exemplary described and it isneedless to say that the example should not be narrowly interpreted.

In this example, the wafer was thermally controlled by the hot jetheater using the N₂ gas employed as the wafer heating means and providedin the spin etching apparatus shown in FIG. 1.

Experimental Example 1

A time necessary to remove a thermal oxide film from the surface of anSi wafer by hydrofluoric acid was measured at each changed hydrofluoricacid flow rate (L/min) to obtain a relation with an etching rate(Å/sec). The wafer was not heated by the wafer heating means. Thecompletion of removal of the oxide film was visually checked based onthe water repellency of a processed surface of the wafer.

An etching processing condition was as follows. A hydrofluoric acidconcentration was 49.5%. A spin rotational speed was 1000 rpm. Achemical solution nozzle was positioned at the center of the wafer. Ahydrofluoric acid temperature was 21° C.

In the above-mentioned processing condition, as shown in FIG. 3, whilethe hydrofluoric acid flow rate was changed from 1 L/min to 0.01 L/min,whether or not there was a variation in etching rate to the hydrofluoricacid flow rate was checked. As a result, there was no variation inetching rate out of a range of 210 Å/sec to 220 Å/sec. Therefore, it wasdetermined that the etching rate was not influenced by the variation inhydrofluoric acid flow rate.

Experimental Example 2

The same processing condition as that in Experimental Example 1 wasemployed except for the fact that the hydrofluoric acid flow rate(L/min) was set to 0.01 L/min, the wafer was heated by the wafer heatingmeans, and a wafer surface temperature was changed as shown in FIG. 4.The time necessary to remove the thermal oxide film from the surface ofthe Si wafer by hydrofluoric acid was measured to obtain a relationbetween the wafer surface temperature (° C.) and the etching rate(Å/sec). A result obtained by measurement is shown in FIG. 4. Thecompletion of removal of the oxide film was checked as in ExperimentalExample 1.

In the above-mentioned processing condition, as shown in FIG. 4, theetching rate was increased by a rise in wafer surface temperature.Therefore, it is determined that the etching rate increases as the wafersurface temperature rises.

INDUSTRIAL APPLICABILITY

According to the present invention, the use efficiency of the chemicalsolution is improved in the spin processing such as the spin etchingprocessing or the spin washing processing, whereby an amount of thechemical solution to be used can be significantly reduced and thechemical solution supply circuit can be simplified to reduce a cost.

1. A spin processing method comprising holding and fixing a wafer on anupper surface of a spin table, and supplying a processing solution to asurface of the wafer by a predetermined amount while rotating the spintable, to process the surface of the wafer, wherein the processingsolution is supplied while the wafer is heated and maintained at apredetermined temperature, to process the wafer.
 2. The spin processingmethod according to claim 1, wherein the predetermined temperature forheating the wafer is equal to or higher than 25° C.
 3. The spinprocessing method according to claim 1, wherein an amount of processingsolution to be supplied is 1 L/min to 0.005 L/min.
 4. A pin processingapparatus, comprising: a spin table rotatably provided and includingwafer holding means on an upper surface thereof; a chemical solutionsupply nozzle for supplying a processing solution to the upper surfaceof the spin table; a wafer heating means for heating a wafer held andfixed on the upper surface of the spin table; a wafer temperaturedetecting means for detecting a temperature of the wafer; and atemperature control circuit for controlling the wafer heating meansbased on a detection temperature signal from the wafer temperaturedetecting means.
 5. The spin processing apparatus according to claim 4,wherein the wafer heating means is an N₂ hot jet means for spraying apressurized and heated nitrogen gas.
 6. The spin processing apparatusaccording to claim 4, wherein the wafer heating means is an air hot jetmeans for spraying pressurized and heated air.
 7. The spin processingapparatus according to claim 4, wherein the wafer heating means is aninfrared spot light means for emitting infrared light in a spot-shapedmanner.
 8. The spin processing apparatus according to claim 4, whereinthe wafer heating means comprises a heating member provided in the waferholding means, with which a temperature can be adjusted.
 9. The spinprocessing method according to claim 2, wherein an amount of processingsolution to be supplied is 1 L/min to 0.005 L/min.